Is it normal to want to sleep with a younger guy?

Whenever I sleep with a guy my own age, I feel like he is grading me on how good I am in bed and that I have to perform for him rather than focus on my own pleasure, and consequently I end up not enjoying it that much. My little brothers 16, and he brought his friend round recently - this boy was tall and good looking, but slim and still clearly pretty young (he was also 16). I felt attracted to him, and started thinking about what it would be like to sleep with a guy with little or no sexual experience. I'm nearly 21. I wouldn't want to sleep with a virgin my own age because (I know this is going to piss alot of people off, sorry but in my experience its true) they arent as attractive as these younger lads who simply havent had the opportunity yet. IIN?